Lignans of Araucaria angustifolia and 13C NMR analysis of some phenyltetralin lignans

Secoisolariciresinol monomethyl ether and lariciresinol-4-methyl ether were isolated from the knots of dead trees of Araucaria angustifolia. On the basis of spectral evidence, the position of the OH group was located in these compounds. The ¹³C NMR spectra of the phenyltetralin lignans galbulin, galcatin, isogalcatin and cyclogalgravin have also been recorded and the signals assigned, based on the methyl shifts of cyclogalgravin.